Dark matter or not dark matter? That is the question when it comes to the origin of intriguing X-ray signals scientists have found coming from space.
In a theory paper published today in Physical Review Letters, scientists have suggested a surprisingly simple way of finding the answer: by setting up a speed trap for the enigmatic particles.
Eighty-five percent of all matter in the universe is dark: It doesn’t emit light, nor does it interact much with regular matter other than through gravity.
The nature of dark matter remains one of the biggest mysteries of modern physics. Most researchers believe that the invisible substance is made of fundamental particles, but so far they’ve evaded detection. One way scientists hope to prove their particle assumption is by searching the sky for energetic light that would emerge when dark matter particles decayed or annihilated each other in space.
Over the past couple of years, several groups analyzing data from two X-ray satellites—the European Space Agency’s XMM-Newton and NASA’s Chandra X-ray space observatories—reported the detection of faint X-rays with a well-defined energy of 3500 electronvolts (3.5 keV). The signal emanated from the center of the Milky Way; its nearest neighbor galaxy, Andromeda; and a number of galaxy clusters.
Some scientists believe it might be a telltale sign of decaying dark matter particles called sterile neutrinos—hypothetical heavier siblings of the known neutrinos produced in fusion reactions in the sun, radioactive decays and other nuclear processes. However, other researchers argue that there could be more mundane astrophysical origins such as hot gases.
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